Pawl-and-ratchet mechanism.



No. 856,365. PATENTED JUNE ll, 1907. DE WITT C. PRESGOTT.

PAWL AND RATGHET MBGHANISM.

VAPPLICATION FILED AUG. 27. 190B,

familia/afs' ejlff'n formal DE WITT C. PRESCOTT, CF CHICAGO, ILLINOIS.v

PAWLANDRATCHET IVIECHANISIVI.

Specification of lLetters Patent.

Patented June 11, 190'?.

Application ined August 27,1906. semi No. 332,198.

.To all wiz/mn, it m/tg/ concern:

Be it known that I, DE VITT C. PREscoTT, a citizen of the United States, and a resident of Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Pawl-and-Ratchet Mechanism, of which the following is a specification, and which are illustrated in the accompanying drawings, forming a part thereof.

The invention relates to pawl and ratchet mechanism particularly adapted for use in saw-mill set-works, and, as illustrated, comprising a pair of pawl carriers adapted to act in alternation upon a ratchet wheel, the invention relating more particularly to mechanism for lifting the pawls out of engagement with the ratchet teeth to permit a reversal of the ratchet wheel.

The object of the invention is to simplify devices of this kind and secure a high degree of efiiciency; and the invention consists of the device hereinafter described and illustrated in the accompanying drawings, in which- Figure 1 is a sectional view of a pawl casing and ratchet wheel, the pawl-lifting mechanism being shown in elevation and in position for raising the pawls; Fig. 2 is a similar view, the lifting mechanism being out of action; Fig. 3 is a view of the pawl casing partly ona radial section and partly in elevation; Fig. 4 is a detail section of a portion of the ratchet wheel and showing a modified form of pawllifting mechanism.

The device is shown as mounted upon a support, such as a saw-mill carriage, one sill of which is represented at 10. A shaft, adapted to be rotated by means of a ratchet wheel, is represented at 11, its bearings not being shown. Upon this shaft is keyed a ratchet wheel 12, having a rim of sufficient width to cooperate with two sets of pawls carried, respectively, by the pawl carriers 13, 14, which are annular in form and are journaled upon the hub 15 of the ratchet wheel. Each pawl carrier is provided with a plurality of pawls 16, vas shown five in number, which are pivoted upon pins 17, one end of which is set in the disk wall of the carrier and the other end in an overhanging and inturned flange 1S. The pawl carriersare oscillated from a crank shaft 19 having two crankarms 20, 21, each of which is connected by a link 22, 23, with one of the pawl carriers.

The peripheral face of the ratchet wheel 12 is centrally and annularly channeled, as

shown at 24, and within this channel is housed the-pawl-lifting device which comprises a rigid segmental member 25, the internal diameter ofV which is less than the diameter of the wheel 12 measured from the bottom of the channel 24, and its external face being the arc of the circle followed by the engaging portions of the pawls when the latter are raised. This pawl lifter has at one end a radially-projecting shank 26, pivotally attached to the end of a lever 27, which is fulcrumed on a bracket 28 mounted upon the sill 10. This shank is approximately diametrically opposite the center of the effective portion of the segmental member, that is to say, on the opposite side of the wheel center, and is adapted to move on the radius of the ratchet wheel with which it coincides. This movement of the shank will cause the effective portion of the segmental member to reciprocate away from and toward the center of the wheel, lifting the pawls out of engagement with its teeth or allowing them to advance under the influence of their springs. The length of the effective ortion of this pawl-lifting member is limite by its curvature, and as it is not sufficient to extend through the extreme range of movement of twosets of pawls it is supplemented by a segmental arm 29, having the same curvature as the outer face of the segment 25, and pivoted to the latter at one end, its free end being pivotally connected to the lever 27. illustrated in Figs. 1 and 2, the pivot of this arm passes through a slot in an arm 30 projecting laterally from the lever, and in the form of construction shown in Fig. 4 the connection with the lever is by means of a link 81.

The pawls 16 are of sufficient width to overlap the channel 24, and hence are in position to be engaged by the pawl lifter when the latter is moved outwardly. When this outward movement occurs the free end of the arm 29 is raised, thereby bringing both members of the pawl lifter beyond the face of the ratchet wheel and disengaging all of the pawls from its teeth. The lifting action is positive, and hence uniform, and is practically frictionless.

I claim as my invention- 1. In combination, a ratchet-wheel, a pawl carrier, a rigid segmental pawl lifter movable in a path substantially parallel with a diameter of the ratchet-wheel and across the circumferential line thereof, and a pawl In the form of construction IOO ITO

LTI

mounted on the carrier and crossing the path of the lifter.

2. In combination, a ratchet-Wheel, a paWl carrier, a rigid segmental pawllifter movable across the circumferential line of the ratchet teeth, there being a shank projecting radially from the lifter diametrically opposite its effective portion, and a paWl mounted on the carrier and crossing the path of the lifter.

3. In combination, a ratchet-Wheel, a paWl carrier, a rigid segmental paWl lifter movable across the circumferential line of the ratchet teeth, there being a shank projecting radially from the lifter diametrically opposlte its effective portion, a lever attached to the shank, and a paWl mounted on the carrier and crossing the path of the lifter.

4. In combination, a ratchet Wheel, a paWl carrier, a rigid segmental pawl lifter movable across the circumferential line of the ratchet teeth, a segmental arm pivotally attached to the 'first-named segment, there being a shank projecting radially from the lifter diametrically opposite its effective portion, a lever attached to the shank and segmental arm, and a paWl mounted on the carrier and crossing the path of the lifter. I

5. In combination, a ratchet Wheel, a paWl carrier, a rigid segmental paWl lifter movable across the circumferential line of the ratchet teeth, a segmental arm pivotally attached to the first-named segment, there being a shank projecting radially from the lifter diametrically opposite its effective portion, a lever attached to the shank, a link connecting the segmental arm with the lever above its ful crum, and a paWl mounted on the carrier and crossing the path of the lifter.

6. In combination, a ratchet Wheel, a paw] carrier, paWls mounted on the .carrier and coacting With the Wheel, a jointed pawl lifter housed Within the circumferential line of the' ratchet teeth, means for moving the lifter outward and flexing it to approximately the curvature of the line of the apeXes of the teeth.

7. In combination, a ratchet Wheel, a paWl carrier, paWls mounted on the carrier and co acting with the Wheel, a jointed paWl lifter housed Within the circumferential line of the ratchet teeth, and means for moving the lifter outward.

DE WITT C. PRESCOTT.

Witnesses:

E. M. KLATCHER, CHARLEs B. GILLsoN. 

